Exhaust gas purifying system and exhaust gas purifying catalyst body for gasoline engine

Abstract

An exhaust gas purifying system for a gasoline engine with high NH3 purifying performance after duration is provided. The exhaust gas purifying system for a gasoline engine disclosed herein is configured to be disposed in an exhaust path of the gasoline engine. The exhaust gas purifying system includes an upstream catalyst converter including a first catalyst body and a downstream catalyst converter including a second catalyst body. The first catalyst body contains a catalyst precious metal. The second catalyst body has a structure in which an NH3 adsorption layer and a catalyst layer are stacked on a base material. The NH3 adsorption layer of the second catalyst body contains a zeolite as an NH3 adsorber. The catalyst layer of the second catalyst body contains a catalyst precious metal and an OSC material.

1 . An exhaust gas purifying system for a gasoline engine configured to be disposed in an exhaust path of the gasoline engine, the exhaust gas purifying system comprising an upstream catalyst converter including a first catalyst body and a downstream catalyst converter including a second catalyst body, wherein
 the first catalyst body contains a catalyst precious metal,   the second catalyst body has a structure in which an NH 3  adsorption layer and a catalyst layer are stacked on a base material,   the NH 3  adsorption layer of the second catalyst body contains a zeolite as an NH 3  adsorber, and   the catalyst layer of the second catalyst body contains a catalyst precious metal and an OSC material.   
     
     
         2 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , wherein the NH 3  adsorption layer is stacked on a lower layer side relative to the catalyst layer in the second catalyst body. 
     
     
         3 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , wherein the zeolite is a CHA-type zeolite carrying Cu. 
     
     
         4 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , further comprising a gasoline particulate filter between the upstream catalyst converter and the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         5 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , further comprising a gasoline particulate filter on a downstream side relative to the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         6 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , wherein the first catalyst body of the upstream catalyst converter is a tandem type catalyst body including an upstream side catalyst body and a downstream side catalyst body. 
     
     
         7 . The exhaust gas purifying system for a gasoline engine according to  claim 6 , further comprising a gasoline particulate filter between the upstream catalyst converter and the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         8 . The exhaust gas purifying system for a gasoline engine according to  claim 6 , further comprising a gasoline particulate filter on a downstream side relative to the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         9 . The exhaust gas purifying system for a gasoline engine according to  claim 6 , wherein the downstream side catalyst body of the first catalyst body has a function as a gasoline particulate filter. 
     
     
         10 . The exhaust gas purifying system for a gasoline engine according to  claim 1 , wherein the first catalyst body of the upstream catalyst converter has a function as a gasoline particulate filter. 
     
     
         11 . An exhaust gas purifying catalyst body for a gasoline engine, comprising:
 a base material;
 an NH 3  adsorption layer stacked on the base material; and 
 a catalyst layer stacked on the NH 3  adsorption layer, wherein 
 the NH 3  adsorption layer contains a zeolite as an NH 3  adsorber, and an OSC material, and 
 the catalyst layer contains a catalyst precious metal and an OSC material. 
   
     
     
         12 . The exhaust gas purifying catalyst body for a gasoline engine according to  claim 11 , wherein the NH 3  adsorption layer further contains a catalyst precious metal. 
     
     
         13 . The exhaust gas purifying system for a gasoline engine according to  claim 2 , wherein the zeolite is a CHA-type zeolite carrying Cu. 
     
     
         14 . The exhaust gas purifying system for a gasoline engine according to  claim 2 , further comprising a gasoline particulate filter between the upstream catalyst converter and the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         15 . The exhaust gas purifying system for a gasoline engine according to  claim 3 , further comprising a gasoline particulate filter between the upstream catalyst converter and the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         16 . The exhaust gas purifying system for a gasoline engine according to  claim 2 , further comprising a gasoline particulate filter on a downstream side relative to the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         17 . The exhaust gas purifying system for a gasoline engine according to  claim 3 , further comprising a gasoline particulate filter on a downstream side relative to the downstream catalyst converter in a flowing direction of exhaust gas in the exhaust path. 
     
     
         18 . The exhaust gas purifying system for a gasoline engine according to  claim 2 , wherein the first catalyst body of the upstream catalyst converter is a tandem type catalyst body including an upstream side catalyst body and a downstream side catalyst body. 
     
     
         19 . The exhaust gas purifying system for a gasoline engine according to  claim 3 , wherein the first catalyst body of the upstream catalyst converter is a tandem type catalyst body including an upstream side catalyst body and a downstream side catalyst body. 
     
     
         20 . The exhaust gas purifying system for a gasoline engine according to  claim 2 , wherein the first catalyst body of the upstream catalyst converter has a function as a gasoline particulate filter.